/**
 * ===========================================
 * Java Pdf Extraction Decoding Access Library
 * ===========================================
 *
 * Project Info:  http://www.jpedal.org
 * (C) Copyright 1997-2008, IDRsolutions and Contributors.
 * Main Developer: Simon Barnett
 *
 * 	This file is part of JPedal
 *
 * Copyright (c) 2008, IDRsolutions
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the IDRsolutions nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY IDRsolutions ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL IDRsolutions BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Other JBIG2 image decoding implementations include
 * jbig2dec (http://jbig2dec.sourceforge.net/)
 * xpdf (http://www.foolabs.com/xpdf/)
 * 
 * The final draft JBIG2 specification can be found at http://www.jpeg.org/public/fcd14492.pdf
 * 
 * All three of the above resources were used in the writing of this software, with methodologies,
 * processes and inspiration taken from all three.
 *
 * ---------------
 * HalftoneRegionSegment.java
 * ---------------
 */
package org.jpedal.jbig2.segment.region.halftone;

import java.io.IOException;

import org.jpedal.jbig2.JBIG2Exception;
import org.jpedal.jbig2.decoders.JBIG2StreamDecoder;
import org.jpedal.jbig2.image.JBIG2Bitmap;
import org.jpedal.jbig2.segment.Segment;
import org.jpedal.jbig2.segment.pageinformation.PageInformationSegment;
import org.jpedal.jbig2.segment.pattern.PatternDictionarySegment;
import org.jpedal.jbig2.segment.region.RegionFlags;
import org.jpedal.jbig2.segment.region.RegionSegment;
import org.jpedal.jbig2.util.BinaryOperation;

public class HalftoneRegionSegment extends RegionSegment {
	private HalftoneRegionFlags halftoneRegionFlags = new HalftoneRegionFlags();

	private boolean inlineImage;

	public HalftoneRegionSegment(JBIG2StreamDecoder streamDecoder, boolean inlineImage) {
		super(streamDecoder);

		this.inlineImage = inlineImage;
	}

	@Override
	public void readSegment() throws IOException, JBIG2Exception {
		super.readSegment();

		/** read text region Segment flags */
		readHalftoneRegionFlags();

		short[] buf = new short[4];
		this.decoder.readByte(buf);
		int gridWidth = BinaryOperation.getInt32(buf);

		buf = new short[4];
		this.decoder.readByte(buf);
		int gridHeight = BinaryOperation.getInt32(buf);

		buf = new short[4];
		this.decoder.readByte(buf);
		int gridX = BinaryOperation.getInt32(buf);

		buf = new short[4];
		this.decoder.readByte(buf);
		int gridY = BinaryOperation.getInt32(buf);

		if (JBIG2StreamDecoder.debug) System.out.println("grid pos and size = " + gridX + ',' + gridY + ' ' + gridWidth + ',' + gridHeight);

		buf = new short[2];
		this.decoder.readByte(buf);
		int stepX = BinaryOperation.getInt16(buf);

		buf = new short[2];
		this.decoder.readByte(buf);
		int stepY = BinaryOperation.getInt16(buf);

		if (JBIG2StreamDecoder.debug) System.out.println("step size = " + stepX + ',' + stepY);

		int[] referedToSegments = this.segmentHeader.getReferredToSegments();
		if (referedToSegments.length != 1) {
			System.out.println("Error in halftone Segment. refSegs should == 1");
		}

		Segment segment = this.decoder.findSegment(referedToSegments[0]);
		if (segment.getSegmentHeader().getSegmentType() != Segment.PATTERN_DICTIONARY) {
			if (JBIG2StreamDecoder.debug) System.out.println("Error in halftone Segment. bad symbol dictionary reference");
		}

		PatternDictionarySegment patternDictionarySegment = (PatternDictionarySegment) segment;

		int bitsPerValue = 0, i = 1;
		while (i < patternDictionarySegment.getSize()) {
			bitsPerValue++;
			i <<= 1;
		}

		JBIG2Bitmap bitmap = patternDictionarySegment.getBitmaps()[0];
		int patternWidth = bitmap.getWidth();
		int patternHeight = bitmap.getHeight();

		if (JBIG2StreamDecoder.debug) System.out.println("pattern size = " + patternWidth + ',' + patternHeight);

		boolean useMMR = this.halftoneRegionFlags.getFlagValue(HalftoneRegionFlags.H_MMR) != 0;
		int template = this.halftoneRegionFlags.getFlagValue(HalftoneRegionFlags.H_TEMPLATE);

		if (!useMMR) {
			this.arithmeticDecoder.resetGenericStats(template, null);
			this.arithmeticDecoder.start();
		}

		int halftoneDefaultPixel = this.halftoneRegionFlags.getFlagValue(HalftoneRegionFlags.H_DEF_PIXEL);
		bitmap = new JBIG2Bitmap(this.regionBitmapWidth, this.regionBitmapHeight, this.arithmeticDecoder, this.huffmanDecoder, this.mmrDecoder);
		bitmap.clear(halftoneDefaultPixel);

		boolean enableSkip = this.halftoneRegionFlags.getFlagValue(HalftoneRegionFlags.H_ENABLE_SKIP) != 0;

		JBIG2Bitmap skipBitmap = null;
		if (enableSkip) {
			skipBitmap = new JBIG2Bitmap(gridWidth, gridHeight, this.arithmeticDecoder, this.huffmanDecoder, this.mmrDecoder);
			skipBitmap.clear(0);
			for (int y = 0; y < gridHeight; y++) {
				for (int x = 0; x < gridWidth; x++) {
					int xx = gridX + y * stepY + x * stepX;
					int yy = gridY + y * stepX - x * stepY;

					if (((xx + patternWidth) >> 8) <= 0 || (xx >> 8) >= this.regionBitmapWidth || ((yy + patternHeight) >> 8) <= 0
							|| (yy >> 8) >= this.regionBitmapHeight) {
						skipBitmap.setPixel(y, x, 1);
					}
				}
			}
		}

		int[] grayScaleImage = new int[gridWidth * gridHeight];

		short[] genericBAdaptiveTemplateX = new short[4], genericBAdaptiveTemplateY = new short[4];

		genericBAdaptiveTemplateX[0] = (short) (template <= 1 ? 3 : 2);
		genericBAdaptiveTemplateY[0] = -1;
		genericBAdaptiveTemplateX[1] = -3;
		genericBAdaptiveTemplateY[1] = -1;
		genericBAdaptiveTemplateX[2] = 2;
		genericBAdaptiveTemplateY[2] = -2;
		genericBAdaptiveTemplateX[3] = -2;
		genericBAdaptiveTemplateY[3] = -2;

		JBIG2Bitmap grayBitmap;

		for (int j = bitsPerValue - 1; j >= 0; --j) {
			grayBitmap = new JBIG2Bitmap(gridWidth, gridHeight, this.arithmeticDecoder, this.huffmanDecoder, this.mmrDecoder);

			grayBitmap.readBitmap(useMMR, template, false, enableSkip, skipBitmap, genericBAdaptiveTemplateX, genericBAdaptiveTemplateY, -1);

			i = 0;
			for (int row = 0; row < gridHeight; row++) {
				for (int col = 0; col < gridWidth; col++) {
					int bit = grayBitmap.getPixel(col, row) ^ grayScaleImage[i] & 1;
					grayScaleImage[i] = (grayScaleImage[i] << 1) | bit;
					i++;
				}
			}
		}

		int combinationOperator = this.halftoneRegionFlags.getFlagValue(HalftoneRegionFlags.H_COMB_OP);

		i = 0;
		for (int col = 0; col < gridHeight; col++) {
			int xx = gridX + col * stepY;
			int yy = gridY + col * stepX;
			for (int row = 0; row < gridWidth; row++) {
				if (!(enableSkip && skipBitmap.getPixel(col, row) == 1)) {
					JBIG2Bitmap patternBitmap = patternDictionarySegment.getBitmaps()[grayScaleImage[i]];
					bitmap.combine(patternBitmap, xx >> 8, yy >> 8, combinationOperator);
				}

				xx += stepX;
				yy -= stepY;

				i++;
			}
		}

		if (this.inlineImage) {
			PageInformationSegment pageSegment = this.decoder.findPageSegement(this.segmentHeader.getPageAssociation());
			JBIG2Bitmap pageBitmap = pageSegment.getPageBitmap();

			int externalCombinationOperator = this.regionFlags.getFlagValue(RegionFlags.EXTERNAL_COMBINATION_OPERATOR);
			pageBitmap.combine(bitmap, this.regionBitmapXLocation, this.regionBitmapYLocation, externalCombinationOperator);
		}
		else {
			bitmap.setBitmapNumber(getSegmentHeader().getSegmentNumber());
			this.decoder.appendBitmap(bitmap);
		}
	}

	private void readHalftoneRegionFlags() throws IOException {
		/** extract text region Segment flags */
		short halftoneRegionFlagsField = this.decoder.readByte();

		this.halftoneRegionFlags.setFlags(halftoneRegionFlagsField);

		if (JBIG2StreamDecoder.debug) System.out.println("generic region Segment flags = " + halftoneRegionFlagsField);
	}

	public HalftoneRegionFlags getHalftoneRegionFlags() {
		return this.halftoneRegionFlags;
	}
}